Hi
Mr Mikewong and Mr Nico Ras
as Mr Juma said load 8Ω is connected in parallel with the capacitor 2,2 mf based on that if there are ringing let's talk more technical specialists.
I am no expert technician.
However I have tried the amp with a load 8Ω with square wave 1 khz 10khz 40khz 100khz full swing 50-60 V peak -peak and i have not at all ringing.
Next days i will show more photo with that test .
Mr Mikewong and Mr Nico Ras
as Mr Juma said load 8Ω is connected in parallel with the capacitor 2,2 mf based on that if there are ringing let's talk more technical specialists.
I am no expert technician.
However I have tried the amp with a load 8Ω with square wave 1 khz 10khz 40khz 100khz full swing 50-60 V peak -peak and i have not at all ringing.
Next days i will show more photo with that test .
Guys, be serious - there has to be ringing when amp is loaded with 8R+2u2. It's avoidable only with overcompensation and that's one of the great ways to ruin every amp....
The scope shots show a pretty stable amplifer if the laod you are driving is indeed 8 Ohms in //with 2.2 microfarads. You will get overshoot and some ringing with that kind of load - it is brutal. Just to confirm this to everyone why dont you post the screen shots of the amp driving a straight 8 Ohm resistive load?
Anyway', looks like a lot of effort has gone into these clones - nice job!
Anyway', looks like a lot of effort has gone into these clones - nice job!
This is load test in simulation of the schematic on page one.
Red line pure 8 ohm load
Green line 8 ohm / 100 nF
Blue line 8 ohm / 2.2 uF
This conforms that the original MM9.2 amp is not perfect with capacitive load.
Note the rise time with pure resistive load and with 100 nF: <500 nS as per GM datasheet.
Red line pure 8 ohm load
Green line 8 ohm / 100 nF
Blue line 8 ohm / 2.2 uF
This conforms that the original MM9.2 amp is not perfect with capacitive load.
Note the rise time with pure resistive load and with 100 nF: <500 nS as per GM datasheet.
Attachments
You could have said 8ohm in parallel with 2u2 OR 8R//2u2. Not just with, it is a nebulous statement. My psychic abilities are lacking a little.
Nico
Ringing .....no, over shoot.. yes, the good ones show very little , very , very little and no ringing. Now try the same test again @ 4 ohm ...
WATCH OUT ! ......
Audio Power Amplifier Design Handbook
Douglas Self
((((((It is usual to test amplifier transient response with a square wave while the output is loaded with 8 Ω and 2 μ F in parallel to simulate an electrostatic loudspeaker, as this is often regarded as the most demanding condition. However, there is an inductor in the amplifier output, and when there is significant capacitance in the load they resonate together, giving a peak in the frequency response at the HF end, and overshoot and ringing on fast edges.
This test therefore does not actually examine amplifier response at all, for the damped ringing that is almost universally seen during these capacitive loading tests is due to the output inductor resonating with the test load capacitance, and has nothing whatever to do with amplifier stability.
The ringing is usually around 40 kHz or so, and this is much too slow to be blamed on any normally compensated amplifier. The output network adds ringing to the transient response even if the amplifier itself is perfect.)))))))
Douglas Self
((((((It is usual to test amplifier transient response with a square wave while the output is loaded with 8 Ω and 2 μ F in parallel to simulate an electrostatic loudspeaker, as this is often regarded as the most demanding condition. However, there is an inductor in the amplifier output, and when there is significant capacitance in the load they resonate together, giving a peak in the frequency response at the HF end, and overshoot and ringing on fast edges.
This test therefore does not actually examine amplifier response at all, for the damped ringing that is almost universally seen during these capacitive loading tests is due to the output inductor resonating with the test load capacitance, and has nothing whatever to do with amplifier stability.
The ringing is usually around 40 kHz or so, and this is much too slow to be blamed on any normally compensated amplifier. The output network adds ringing to the transient response even if the amplifier itself is perfect.)))))))